Tetraethylammonium chloride (TEAC) is a quaternary ammonium compound with the chemical formula [N(CH2CH3)4]+Cl−, sometimes written as [NEt4]Cl.

It has been used as the source of tetraethylammonium ions in pharmacological and physiological studies, but is also used in organic chemical synthesis.

[5] Details for the preparation of large, prismatic crystals of TEAC·H2O are given by Harmon and Gabriele, who carried out IR-spectroscopic studies on this and related compounds.

[6] These researchers have also pointed out that, although freshly-purified TEAC·H2O is free of triethylamine hydrochloride, small quantities of this compound form on heating of TEAC as the result of a Hofmann elimination: To a large extent, the synthetic applications of TEAC resemble those of tetraethylammonium bromide (TEAB) and tetraethylammonium iodide (TEAI), although one of the salts may be more efficacious than another in a particular reaction.

For example, TEAC produces better yields than TEAB or TEAI as a co-catalyst in a reaction to prepare diarylureas from arylamines, nitroaromatics and carbon monoxide.